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Pretreatment of sulfates before wastewater treatment

Pretreatment of sulfates before wastewater treatment

Pretreatment of sulfates before wastewater treatment

(OP)
I have a 100 gallon per day batch waste stream that contains residual sulfuric acid (about 5%) and formaldehyde(about 2%).  I want to minimize the sulfates going into my biological waste treatment area by pre-treating this stream.  I will experiment with raising the pH with soda ash and then making a floc by adding CaCl2.  I will then be able to decant the clear supernatant into the bio-treat area (then dispose of the greatly reduced volume of solid residue).  Any other cost effective, proven suggestions? Any additives to enhance the floccuating properties? I read some pretty wild economically INfeasible suggestions on these forums, so please make any suggestions practical and not textbook!

RE: Pretreatment of sulfates before wastewater treatment

Instead of "raising the pH with soda ash and then making a floc by adding CaCl2," why not use Ca(OH)2 to do both?
The vast majority of the sulfate will precipitate out by the time you reach pH 7. You may be able to get [SO4] down to about 810 ppm; see Thread161-50054, although this depends upon temperature and common ion effects, too.

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